Substituted alkyl esters of alpha-carboxy aryl penicillins

ABSTRACT

ARYLCHLORO (AND BROMO) CARBONYL KETENES, ARYLCARBOXY KETENE SUBSTITUTED ALKYL ESTERS DERIVED THEREFROM, METHODS FOR THEIR REPARATION AND THE USE OF THE ESTERS AS ACYLATING AGENTS FOR THE PRODUCTION OF SUBSTITUTED ALKYL ESTERS OF A-CARBOXY ARYLACETYL DERIVATIVES OF 6-AMINOPENICELLANIC ACID AND, BY HYDROLYSIS, THE CORRESPONDING ACID DERIVATIVES, ARE DESCRIBED.

States US. Cl. 260-2391 8 Claims ABSTRACT OF THE DISCLOSURE Arylchloro(and bromo) carbonyl ketenes, arylcarboxy ketene substituted alkylesters derived therefrom, methods for their reparation and the use ofthe esters as acylating agents for the production of substituted alkylesters of a-carboxy arylacetyl derivatives of o-aminopenicillanic acidand, by hydrolysis, the corresponding acid derivatives, are described.

BACKGROUND OF THE INVENTION This invention relates to a series of novelderivatives of arylcarboxy ketenes, to methods for their preparation,and to their use as intermediates for further synthesis. Moreparticularly, it relates to a series of novel arylchlorocarbonyl ketenesand to the corresponding bromo analogs; to novel arylcarboxy keteneesters derived therefrom, to the use of the esters as novel acylatingagents for the acylation of amines such as 6-aminopenicillanic acid, andto the novel acyl amines thus produced.

The production of ketenes from malonic acid derivatives is described inthe literature. Staudinger, Helv. Chim. Acta 8, 306 (1925), for example,prepared a series of low-molecular-weight dialkyl ketenes by the thermaldecomposition of di(lower)alky1 substituted malonic anhydrides. In amodification of this method using mixed anhydrides prepared fromdisubstituted malonic acids and diphenyl ketene, Staudinger et al.,ibid, 6, 291 (1923) and Ber. 46, 3539 (1913) prepared variousdisubstituted ketenes by thermal decomposition. A still further methodcomprises the dehalogenation of a-halo acyl halides with zinc(Staudinger, Ann. 356, 71 (1907); 380, 298 (1911) By extension of thisreaction, Staudinger et al., Ber. 42, 4908 (1909), prepared ethylcarbethoxy ketene by the dehalogenation of dIGIhYI-zx-bIOHlO-ot-GthYlmalonate. Another method, the decomposition of diazo ketones, has beenused to prepare certain diaryl ketenes (Smith et al., Org. Syntheses 20,47, 1940; Gilman et al., Rec. trav. chim. 48, 464, 1929). It is furtherknown that certain disubstituted acetyl chlorides undergodehydrohalogenation under the influence of tertiary amines to form ketoketenes. This method, however, appears to be limited to the preparationof certain aryl and high-molecular-weight keto ketenes, all of which arerelatively resistant to dimerization (Staudinger et al., Ber. 41, 594,1908).

The reaction of phenylmalonic acid with phosphorus pentachloride (1:2molar ratio) in ether solution is reported by Sorm et al. (CollectionCzechoslov. Chem. Communs. 20, 593-6, 1955) to produce phenylmalonylchloride. The same authors report (loc. cit.) that when the reaction isconducted in the absence of a solvent at the reflux temperature,phenylchloromalonyl chloride is produced.

The preparation of lower alkyl esters of phenylcarboxy ketene by thermaldecomposition of diazoketo esters has been described by Staudinger eta1. (Ber. 49, 2522, 1916). However, the method used by Staudinger israther complex and results, on an overall basis, in rather poor yields.The process of the present invention for making such esters, on theother hand, is simple and productive of satisfactory yields.

"ice 3,557,094 Patented Jan. 19, 1971 The use of ketenes as acetylatingagents is well known in the art. The acylation of amino groups by meansof simple or mixed acid anhydrides, acid halides, acid azides,fl-thiolacetones, acylated enols and carboxylic acids with carbodiimidesis also known in the art (Sheehan, US. Pat. 3,159,617, Dec. 1, 1964).However, the introduction of tat-carboxy arylacetyl groups into6-aminopenicillanic acid has, up until now, been limited to the use of asimple or mixed anhydride, an acid halide of an arylmalonic acid or anaryl malonic acid ester as acylating agent (US. Pat. 3,142,673, BritishPat. 1,004,670).

SUMMARY OF THE INVENTION It has now been unexpectedly found that avariety of aryl chlorocarbonyl ketenes, and the corresponding bromoanalogs, can readily be prepared by the reaction of aryl malonic acidswith a halogenating agent followed by thermal elimination of hydrogenhalide and vacuum distillation of the reaction product thus formed. Theprocess and the compounds are summarized by the reaction:

wherein R broadly referred to herein as an aryl group, is selected fromthe group consisting of: thienyl, furyl, pyridyl, phenyl, andsubstituted phenyl wherein the substituent is selected from the groupconsisting of (lower)- alkyl, chloro, bromo, (lower)alkoxy,di(lower)alkylamino and tn'fluoromethyl, and X is selected from thegroup consisting of chloro and bromo.

The process of this invention, in view of the teaching of Sorm et al.(10c. cit.) that phenylmalonyl chloride and phenylchloromalonyl chlorideare obtained by the action of phosphorous pentachloride on phenylmalonicacid in the presence of a solvent and the products recovered by vacuumdistillation, is most surprising and unexpected. Repetition of the Sormet al. procedure for making phenylmalonyl chloride has been found toproduce phenylchlorocarbonyl ketene rather than phenylmalonyl chloride.The existence of the ketene compound was completely unrecognized by Sormet al.

The process, in general, comprises reacting an aryl substituted malonicacid with a halogenating agent selected from the group consisting ofP(X) P(X) PO(X) and SO(X) wherein X is as defined above at a temperatureof from about 0 C. to about 50 C. The dihalide thus produced isthermally decomposed at about 100 C. to provide the aryl halocarbonylketene.

The arylhalocarbonyl ketenes exhibit a dual functionality and react bothas acid halides and ketenes. They are, therefore, valuable asintermediates for further synthesis. Alcohols (R OH) for example, reactwith the arylhalocarbonyl ketenes at low temperatures, e.g. from about'70 C. to about 30 C. to produce the corresponding esters of arylcarboxy ketenes which are useful as acylating agents. Reaction appearsto occur first with the ketene group to form transient intermediatewhich rearranges with elimination of hydrogen halide to the arylcarboxyketene ester.

The novel arylcarboxy ketene esters of this invention are especiallyvaluable as agents for the acylation of amines with production of estersof a-carboxy-a-arylacetyl amines. They are particularly useful for theacylation of amines such as 6-aminopencillanic acid for the productionof known and novel antibacterial agents. Prior art methods forintroducing tit-carboxy arylacetyl groups into amino compounds such as6-aminopenicillanic acid have made use of acid anhydrides, mixed orsimple, or acid halides of aryl malonic acids. The use of the prioracylating agents require extreme caution during reaction and recoverysteps in order to obtain satisfactory yields and avoid decarboxylationof the carboxy group. The acylatin agents of this invention on the otherhand react smoothly and rapidly with amines at low temperatures andproduce no undesirable by-products.

The acid halides and esters of the aryl carboxy ketenes form 3 arylsubstituted 2 oxo-oxetenes- (1,3-epoxypropenes) in solution. Thesecompounds react in a manner analogous to that of the compounds fromwhich they are derived.

The above reactions are summarized in the following sequence:

IV IlI wherein R and X are as defined above;

R is selected from the group consisting of substituted lower alkylwherein the substituent is selected from the group consisting of atleast one of:

chloro bromo nitro carbo(lower alkoxy) lower alkanoyl lower alkoxy cyano(lower)alkyl mercapto (lower)alkyl sulfinyl (lower)alkyl sulfonyl and Ris:

Of the lower alkoxy and lower alkanoyl groups those having from 1 to 4carbon atoms in the alkyl, alkoxy and alkanoyl moieties are preferredsince the reactants bearing such groups are more readily available thanare those required for such groups showing a greater number of carbonatoms.

Also included within the scope of this invention are thepharmaceutically acceptable salts of the novel compounds of Formula IIIin which one or both acid groups are involved in salt formation. Saltssuch as the sodium, potassium, calcium, magnesium, ammonium andsubstituted ammonium salts, e.g. procaine, dibenzylamine,N,N-dibenzylethylenediamine, N,N-bis-(dehydroabietyl) ethylenediamine,l-ephenamine, N-ethylpiperidine, N-benzyl- ,B-phenethylamine,trialkylamines, including triethylamine, as well as salts with otheramines which have been used to form salts with benzylpenicillin areuseful for the preparation of pharmaceutically elegant compositions ofthese valuable antibiotics.

DETAILED DESCRIPTION OF THE INVENTION The production of arylchloro (andbromo) carbonyl ketenes comprises the reaction of an arylmalonic acidwith a halogenatin agent selected from the group consisting of P(X) P(X)PO(X) and SO(X) wherein X is as defined above at temperatures rangingfrom about 0 C. to about 50 C. for periods ranging from about one hourto about 10 hours. The reaction is conducted in the presence of asolvent system, preferably a reaction-inert solvent system. Suitablesolvents are dialkyl ethers, e.g. diethyl ether, dipropyl ether, monoanddimethyl ethers of ethylene glycol and propylene glycol, methylenechloride and chloroform.

The reaction period is, of course, dependent upon the reactiontemperature and the nature of the reactants. However, for a givencombination of reactants, the lower temperatures require longer reactionperiods than do higher temperatures.

The molar proportions of reactants, i.e. arylmalonic acid andhalogenating agent, can vary widely, e.g. up to 1:10 or higher, but forsatisfactory yields should be at least stoichiometric. In actualpractice the stoichiometric ratio of reactants is preferred.

The reactants may be added all at once or separately. If separately, theorder of addition is not critical. However, it appears that the reactionis smoother and subject to fewer side-reactions, as evidenced by thecolor of the reaction mixture, particularly upon distillation, when thearylmalonic acid is added to the halogenating agent. The reactionmixture, under such conditions, generally progresses from a yellow to ared color. The reaction mixture on reverse addition, i.e. the additionof halogenating agent to the arylmalonic acid, progresses from yellow toblack.

The arylhalocarbonyl ketene products are isolated from the reaction bydistillation in vacuo. Because of their great reactivity they aregenerally stored under a nitrogen atmosphere at low temperatures and inthe absence of light.

Reaction of the aryl halocarbonyl ketenes with alcohols is conducted ona 1:1 molar ratio at a temperature of from about C. to about 30 C. whenconversion of the arylhalocarbonyl ketene to a ketene ester is desired.A reaction-inert solvent, such as ethyl ether, methyl ether, dioxane,methylene chloride, chloroform, is desirably used to permit bettermixing and control of the reaction. The use of greater than a 1:1 molarratio of arylhalocarbonyl ketene to alcohol or temperatures above 30 C.produces malonic acid diesters. For example, when two moles of alcoholis used per mole of arylhalocarbonyl ketene the corresponding diester ofthe arylmalonic acid is produced. Halfamides of arylmalonic acid estersare obtained by reacting the arylhalocarbonyl ketenes with an alcoholfollowed by reaction of the resulting arylcarboxy ketene ester with aprimary or secondary amine as is described herein. Isolation of theintermediate ester is not necessary. A tertiary amine may be used asacid acceptor to remove the hydrogen halide produced during formation ofthe ester.

The arylcarboxy ketene esters produced as described above are excellentacylating agents particularly suited for the acylation of amines toproduce a-carboxyaryL acetyl amines. They are especially valuable asagents for the acylation of 6-aminopenicillanic acid.

The acylation of 6-aminopenicillanic acid is conducted at a temperatureof from about 70 C. to about 50 C. and preferably at a temperature offrom about C. to about 30 C. The reaction period is generally from a fewminutes up to about hours. A reaction-inert solvent such as ethylacetate, dioxane, tetrahydrofuran, methyl isobutyl ketone, chloroform ormethylene chloride is generally used to facilitate stirring andtemperature control. It has been found especially convenient to firstform the arylcarboxy ketene ester as described above and to use thereaction mixture, without isolation of the arylcarboxy ketene ester,directly in the amine acylation reaction. In such instances an organicbase, i.e. a tertiary amine such as triethylamine or othertrialkylamine, preferably a tri- (lower alkyl)amine, is used to removethe hydrogen halide produced in formation of the arylcarboxy keteneester. From a practical standpoint, the 6-aminopenicillanic acid is usedas its triethylamine salt. For this reason, methylene chloride is apreferred solvent since the triethylamine salt is readily solubletherein. The sodium or potassium salts of 6-aminopenicillanic acid canalso be used but the preferred salt is the triethylamine salt because ofits greater solubility in the solvent systems used. An excess of theamine to be acylated can, of course, be used as acid acceptor but isgenerally avoided, not only for economic reasons but also to preventpossible ammonolysis of the ester group. The reaction is desirablyconducted under an atmosphere of nitrogen.

The N-acylation reaction can also be conducted in neutral or alkalineaqueous solution by taking advantage of the slower rate of reaction ofthe arylcarboxy ketene esters with water at neutral or alkaline pHlevels relative to the rate of reaction with the amino group. Thereaction is conducted at temperatures ranging from just above thefreezing point of the aqueous system to about 50 C. and preferably atfrom 0 C. to about 20 C. To permit attainment of low temperatures and tofacilitate reaction, it is advantageous to employ a mixed solventsystem, i.e. water plus a water miscible reaction-inert organic solventsuch as dioxane or tetrahydrofuran. The ketene ester is, of course,desirably used as a solution in the same reaction-inert solvent and ispreferably added to the aqueous solution of the 6-aminopenicillanicacid.

The acylated products are isolated by conventional methods. A typicalmethod, for example, comprises evaporating the reaction mixture todryness under reduced pressure, dissolving the residue in citrate buffer(pH 5.5) and extracting the product therefrom with chloroform. Thechloroform extracts are washed with citrate buffer (pH 5.5), dried withanhydrous sodium sulfate and evaporated to dryness. In another method,which is of value for the isolation of acylation products poorly soluble in methylene chloride, or chloroform, the above method is followedbut using n-butanol as extracting solvent in place of chloroform. Theproduct remaining after removal of the n-butanol solvent by evaporationis triturated with ether to produce an amorphous solid.

In still another method, essentially a variation of the above methods,saturated sodium bicarbonate (or potassium bicarbonate) is used in placeof the citrate buffer. This method, of course, produces the sodium (orpotassium) salt of the acylation product. If necessary, to obtain asolid product, the salt is triturated with ether.

In yet another method, the residue remaining after removal of thevolatiles from the reaction mixture is taken up in water at pH of fromabout 2.3 to 2.9, usually about pH 2.7, and the free acid form of theacylation product extracted from the acid solution with chloroform,ether, n-butanol or other suitable solvent. The chloroform, ether orn-butanol extract is then washed with aqueous acid (pH 2.32.9) and theproduct recovered by lyophilization or by conversion to asolvent-insoluble salt as by neutralization with an n-butanol solutionof sodium or potassium 2-ethylhexanoate.

The esters are converted by known methods to the corresponding acids as,for example, by mild base treatment or enzymatically with an esterasesuch as liver homogenate.

The valuable products of this invention are remarkably effective intreating a number of susceptible gram-positive and gram-negativeinfections in animals, including man. For this purpose, the purematerials or mixtures thereof with other antibiotics can be employed.They may be administered alone or in combination with a pharmaceuticalcarrier selected on the basis of the chosen route of administration andstandard pharmaceutical practice. For example, they may be administeredorally in the form of tablets containing such excipients as starch, milksugar, certain types of clay, etc., or in capsules alone or in admixturewith the same or equivalent excipients. They may also be administeredorally in the form of elixirs or oral suspensions which may containflavoring or coloring agents, or be injected parenterally, that is, forexample, intramuseularly or subcutaneously. For parenteraladministration they are best used in the form of a sterile aqueoussolution which may be either aqueous such as water, isotonic saline,isotonic dextrose, Ringers solution, or non-aqueous such as fatty oilsof vegetable origin (cotton seed, peanut oil, corn, sesame) and othernonaqueous vehicles which will not interfere with the therapeuticefficiency of the preparation and are non-toxic in the volume orproportion used (glycerol, propylene glycol, sorbitol). Additionally,compositions suitable for ex temporaneous preparation of solutions priorto administration may advantageously be made. Such compositions mayinclude liquid diluents, for example, propylene 3 glycol, diethylcarbonate, glycerol, sorbitol, etc.; buffering agents, as well as localanesthetics and inorganic salts to afford desirable pharmacologicalproperties.

The oral and parenteral dosage levels for the herein described compoundsare, in general, on the order of up 0 to 200 mg./kg. and 100 mg./kg. ofbody weight per day,

respectively.

Many of the penicillin ester compounds of this invention exhibitimproved absorption on oral administration over that produced by thecorresponding free acid or alkali metal salt forms. They, therefore,represent convenient and effective dosage forms of the u-carboxy arylpenicillins.

Additionally, many of the esters described herein, although inactive orof relatively low activity against gramnegative organisms per se, aremetabolized to the parent acid, i.e. ot-carboxybenzylpenicillin, wheninjected parenterally into the animal, including the human, body. Therate of metabolic conversion of such esters to the parent acid occurs atsuch a rate as to provide an effective and prolonged concentration ofthe parent acid in the animal body. In effect, such esters act as depotsources for the parent acid. Especially useful in this respect are thosecompounds wherein R is l-lower alkoxy-2,2,2-trifiuoroethyl or l-loweralkoxy-Z,2,2-trichloroethyl. The 1- ethoxy 2,2,2 trichloroethyl ester ofa-carboxy benzyl penicillin, for example, when administered orally atlevels of 200 and 100 mg./ kg. to mice infected with Escherichia 0011'produced survival rates of and 60%, respectively. When administeredsubcutaneously at levels of 200 and mg./kg. to similarly infected micesurvival rates of 70% and 70%, respectively, were obtained.

The antimicrobial spectra of several esters of a-carboxybenzylpenicillin against Staphylococcus aureus and Escherichia coli arepresented below. The tests were run under standardized conditions inwhich nutrient broth containing various concentrations of the testmaterial'was seeded with the particular organism specified, and theminimum growth (MIC) at which growth of each organism failed to occurwas observed and recorded. The test materials have the following formula4 and were tested as their sodium or potassium salts. Benzylpencillin (Ksalt) when thus tested gave values of 0.156, 100 vs. S. aureus and E.0011', respectively.

R2 S. uurcus E. coli Methyl 0. 625 50 Ethyl .v 1. 25 100 6. 25 200t-Buty1. l. 50 100 2-methylpr0pyl 3. 12 100 l'lexyl s 200 Octyl. 200 200Tetradccyl 200 200 2-cyanoethyl 1. E 6. 25 Z-methoxyethyL 3. 1'. 1002-acetoxyethyl. 3. 12 200 l-(l-carbethoxy) ethyl 100 2002-(1,2,3-tricarbethoxy)propyL l. 50 200 2-chloroethyl s s 50 2002,2,2-trichlorethyl s 100 200 2-(2-tritlu0romethyl)pr0pyl s 0. T8 2001-eth0xy-2,2,Z-tritluoroethyl s O. 7 8 5t) 1-ethoxy-2,2,2-trichloroethyl(J. 78 12. 5 1-isopropoxy-2,2,2-trichlor0ethyl l. 50 100l-butoxy-2,2,2-trichlroethyl. 0. 3t) 50 Carbethoxy ethoxy methyL 25 100D icarbethoxy etlioxy mcthy 1. 56 50 1-(2,3-rlibutyryl0xy)propyl 500 2003-oxobutyl r 50 200 1,1-dimethyl acctonyL. 200 200 2-nitrobutyl Table IIpresents in vivo data for several compounds of this invention in mice(PO=oral and SQ=subcuta neous routes of administration). The values areobtained under standardized conditions. The procedure comprisesproduction of an acute experimental E. coli 266 infection in mice by theintraperitoneal incubation of the mice With a standardized (IO- E. 0011'266 culture suspended in 5% hog gastric mucin. The test compounds, inthe form of their sodium or potassium salts, administered to theinfected mice by a multiple dosing regimen in which the first dose isgiven 0.5 hour after inoculation and is repeated 4, 24 and 48 hourslater. The percent of mice surviving are then determined. 7

The LD of E. coli 266 (the lowest concentration required to produce 100%mortality in mice) is Control animals receive inocula of 10 10- and 10-as a check on possible variation in virulence which can occur.

TABLE II.IN vrvo DATA vs. COLI 266 IN MICE Percent survivorsPhenylchlorocarbonyl ketene (A) To phenylmalonic acid g.) in ethyl ether(100 ml.) there is added phosphorous pentachloride (46 g.). A vigorousreaction occurs. The reaction mixture is refluxed for four hours thenthe ether partially removed by heating on a steam bath. The reactionmixture becomes black When about half the ether is removed and theremaining ether is removed under reduced pressure (at 100 mm.). Theresidue is distilled under vacuum and the fraction boiling at 7590 C. at1.54 mm. collected. The product, a yellow liquid, is redistilled at 74C. and 1.5 mm. It shows a strong peak in the infrared region of thespectrum at 4.69p..

Repetition of this procedure but using 10 g. of phenylmalonic acidinstead of 20 g. produces a less vigorous reaction on addition of thephosphorous pcntuchloride. The same product is obtained.

(B) Phosphorous pentachloride (23 g.) is added over a 5-minute period toa stirred solution of phenylmalonic acid (10 g.) in ethyl ether (50 ml.)initially at a temperature of 0-5 C. The temperature rises to 13 C.during the addition. The mixture is then refluxed for five hours andallowed to stand overnight at room temperature. Removal of the ether at20 mm. produces a dark concentrate which is vacuum distilled to give thedesired product: B.P. -88 C. at 1.5-2.0 mm. and 74 C. at 0.2 mm.

(C) To a stirred solution of phosphorous pentachloride (46 g.) in ethylether ml.) there is added phenylmalonic acid (10 g.) over a two-minuteperiod. The mixture is stirred at room temperature for four hours thenrefluxed for four hours and allowed to stand overnight at roomtemperature. The excess phosphorous pentachloride is filtered off andthe ether boiled off at atmospheric pressure. The reaction mixturegradually progresses in color from dark yellow to red. The residue isdistilled in vacuo to give the product: B.P. 83-86 C. at 1.5 mm. as ayellow liquid.

(D) Repetition of this procedure but using an equivalent amount ofphosphorous oxychloride as halogenating agent in place of phosphorouspentachloride produces the same product.

EXAMPLE II The procedure of Example I-C is repeated but using theappropriate malonic acid derivative in place of phenylmalonic acid toproduce the following compounds.

3 -furyl Z-thienyl 3 -thienyl Z-furyl cr-t Olyl m-tolyl p-tolyla-methoxyphenyl m-methoxyphenyl p-methoxyphenyl a-trifluoromethylphenylp-trifluoromethylphenyl m-trifluoromethylphenyl v-isopropylphenyl p-di-(n-propyl) aminophenyl m-dimethylaminophenyl p-dimethylaminophenyla-dibutylaminophenyl Z-pyridyl 3-pyridyl 4-pyridyl a-bromophenylm-bromophenyl a-chlorophenyl p-chlorophenyl m-chlorophenyla-butoxyphenyl a-dimethylaminophenyl a-diethylaminophenyl EXAMPLE IIIRepetition of the procedures of Examples LC and II but using PBr inplace of PCl produces the corresponding bromo compounds.

EXAMPLE IV Methyl ester of phenylcarboxy ketene To a solution of.phenylchlorocarbonyl ketene (0.5 g.) in dry chloroform (5 ml.) there isadded anhydrous methanol (0.1 ml.) at room temperature. Hydrogenchloride is liberated. The mixture, maintained under an atmosphere ofnitrogen, is stirred for 20 minutes and the product recovered byevaporation of the solvent.

EXAMPLE V A mixture of phenylmalonic acid g.) and thionyl chloride (30ml.) is heated to reflux for six hours to give a clear yellow solution.Removal of the excess thionyl chloride by evaporation provides the crudephenylchlorocarbonyl ketene. The pure compound is obtained bydistillation in vacuo.

EXAMPLE VI Esters of arylcarboxy ketenesGeneral preparation method To asolution of the appropriate aryl halocarbonyl ketene (0.1 mole) inmethylene chloride (sufficient to provide a clear solution and generallyfrom about 5 to ml. per gram of ketene) there is added the properalcohol R OH (0.1 mole). The reaction mixture is maintained under anatmosphere of nitrogen and stirred for a period of from minutes to 3hours, care being taken to exclude moisture. The temperature may rangefrom about -70 C. to about 20 C.

The compounds thus prepared are presented below.

l-methyl-Z-nitroethyl 4-nitrobutyl l-methyl-Z-nitropropyl2,2-dinitroethyl l-methyl-2-chloro-Z-nitroethyl1-trichloromethyl-2-nitroethyl l,1-dimethyl-2,2,2-trichlorethylZ-methoxyethyl 2-ethoxyethyl 2-iso'butoxyethyl 4-ethoxy-n-butyl1,1-dimethyl-2-ethoxyethyl l-cyanoethyl 4-cyanobutyl2-cyanol-methylethyl 1-chloromethyl-Z-cyanoethyl1-cyano-2,Z-dichloropropyl 1-cyano-2,2,2-trichloroethyl 1-methyl-1-(l'-cyano-l-methylethoxy) ethyl Z-acetoxyethyl Z-butyryloxyethyl2-acetoxy-n-butyl carbomethoxymethyl Z-carbethoxyethyl 4-carbethoxybutylZ-carbethoxypropyl l-carbethoxyethyl l-chloromethyl-Z-carb ethoxyethyl1-trichloromethyl-Z-carbomethoxyethyl 1-carbethoxy-2,2-dichloropropyl1-carbomethoxy-2,2,2-trichloroethyll-carbomethoxymethyl-2,2,2-trichloroethyl acetonyl acetonylmethyl4-oxopentyl 1-methyl-4-oxopenty1 1-methyl-3-oxobutyll-acetyll-methylpropyl Z-acetylbutyl 2-acetylpropyl S-oxohexyl1-methoXy-2,2,2-trichlorethyl 1-methoxy-2,2,2-trifiuoroethyl methyl l 0ethyl n-propyl n-butyl sec-butyl t-butyl decyl octadecyl 2-chloroethyl 3-chloropropyl l-methyl-Z-chloroethyl l-ethyl-2-chloroethyll-methyl-Z-chloropropyl 1,l-dimethyl-Z-chloroethyl Z-bromoethyl2-bromo-1-butyl 1,3-dichloropropyl 1,1-dichloromethylethyl2-bromo-3-chloropropyl 1-bromomethyl-2-chloroethyl l,l-dichloromethylethyl l, l -dimethyl-2,Z-dichlorOethyl2,3,3-tribromopropyl 2,2,3 ,3-tetrabromopropyl 2,2,2-trifluoroethyl2-nitroethyl 2,3 -diacetoxypropyl 2,3-distearoyloxypropyl(1,2,3-tricarbomethoxy -2-propyl 2-fluoroethyl2,2,3,3,4,4,4-heptafiuorobutyl EXAMPLE VII bonyl ketenes of Examples IIand III wherein R is 2- furyl, Z-thienyl, 3-thienyl, 2-pyridyl,4-pyridyl, p-tolyl, a-methoxyphenyl, p methoxyphenyl, o'trifiuoromethylphenyl, pchlorophenyl, a-dimethylaminophenyl andp-dimethylaminophenyl. For convenience only the R values are listed.

methyl ethyl n-butyl 2-cyanol -methylpropyl decyl tetradecyl2-chloroethyl 2-chloropropyl 4-chloro-1-buty1 l-methyl-3-chloropropylZ-bromoethyl 1-ethyl-2-bromoethyl 1,3-dichloropropyl2-bromo-3-ch1oropropyl 3,4-dichloro-1-butyl 2,2-dichloroethyl1,1-dimethyl-2,Z-dichloroethyl 2,2,3-tribromopropyl 2,2,3-trichlorobutyl2,2,2-trichloroethyl 2,2,2-trifluoroethyl 3 -nitropropyl Z-nitrobutyl2,2-dinitroethyl 2-chloro-2-nitropropyl 1-trichloromethyl-2-nitroethyll-trifluoromethylethyl 1,1-dimethyl-2,2,2-trifluoroethyl1-ethyl-1-methyl-2,2,2-trichloroethyl Z-methoxyethyl S-sec butoxypropyl4-methoxy-n-butyl 1,1-dimethyl-2-methoxyethyl carbethoxy ethoxymethyl 1l 2-methylmereaptoethyl 3-propylmercaptopropyl 2-methylsulfinylethyl3-propylsulfonylpropyl 2-cyanoethyl 3-cyanopropyl t-butyll-cyano-Z-chloropropyl 1-cyano-2,2-dichloropropyl1-cyano-2,2,2-trichloroethyl l-methyl- 1-( l'-cyanol -methylethoxy propvl Z-acetoxyethyl Z-butyryloxyethyl 3-acetoxypropyl carbomethoxymethyl2-carbethoxyethyl 3-carbobutoxypropyl 2-carbethoxypropyl1-trichloromethyl-2-carbomethoxyethyl 1-carbethoxy-2,2-dichloropropyl1-carbomethoxy-2,2,2-trichloroethyl acetonyl 2-oxopentyl 4-oxopentyl2-acetylbutyl 1-methyl-3-oxohexyl 3-oxopenty1 4-oxohexyl1-ethoxy-2,2,2-trichloroethyl l-methoxy-2,2,2-trifiuoroethyl2,3-diacetoxypropyl 2,3-distearoyloxypropyl l ,2,3-tricarbomethoxy-2-propyl 3-fiuoropropyl 4,4,4-trichlorobutyl chlorodicarbomethoxymethyl1,l-dicarbethoxymethyl-Z-ethoxyethyl Z-butylmercaptoethyl4-ethylmercaptobutyl Z-methylsulfonylethyl 2-ethylsulfinylbutyl EXAMPLEVIII Again following the procedure of Example VI, the arylcarboxyketeneesters listed below are prepared. The aryl group, R for each of the Rvalues given, is m-tolyl, m-methoxyphenyl, p-trifluoromethylphenyl,3-pyridyl, aisopropylphenyl, a-chlorophenyl, tr-bromophenyl,mbromophenyl, m-chlorophenyl, tr-butoxyphenyl, a-butylphenyl,a-diethylaminophenyl, m-dimethylaminophenyl, p-di-(n-propyl)aminophenyl,3-furyl and a-dibutylaminophenyl.

2-ethylsulfonylethyl Z-ethylmercaptoethyl methyl n-propyl t-butyldodecyl octadecyl 3-chloropropyl 3-chlorol-butyl 1-methy1-2-chloropropyl1, l-dimethyl-Z-chloroethyl 2-bromopropyl 4-bromo-1-butyl1,3-dichloropropyl 1,4-dibromo-2-butyl 2,2-dichloroethy12,2,3-trichlorobutyl 2,2,2-trichloroethyl 2- Z-trifiuoromethyl propyl'l-nitroethyl Z-nitrobutyl 4-nitrobutyl 1 2 l-methy1-2-nitro propyl2-chloro-2-nitropropyl l-trifiuoromethylethyl 2-methoxyethyl2-isobutoxyethyl 3 -methoxypropyl 4-ethoxy-n-butylZ-t-butylmercaptoethyl 2-methylsulfinyl-Z-methylethyl2-methylmercapto-Z-methylethyl Z-cyanoethyl 3 -cyanopropyl1-cyano-2-chloropropyl 1-cyano-2,2,2-trichloroethyll-methyl-l-(1'-cyano-1-methylethoxy)propyl Z-propionyloxyethyl2-acetoxy-n-butyl 4-propionyloxy-n-butyl carbomethoxymethyl2-carbethoxyethyl 3-carbomethoxypropyl l-carbethoxyethyl1-trichloromethyl-2-carbomethoxyethyl 1-carbethoxy-Z-chloropropyl1-carbomethoxy-2,2,2-trichloroethyll-carbomethoxymethyl-2,2,2-trichloroethyl acetonyl 2-0xopentyl2-acetylbutyl 3-oxopentyl 4-oxohexyl l-methoxy-2,2,2-trichlorethyl2,3-diacetoxypropyl Z-fluoroethyl 1-trifiuoromethyl2-nitroethyl car'bethoxyethoxymethyl Z-ethylsulfinylethyl EXAMPLE IX eneral methods foracylation of 6-aminopenicillanic acid To a solution of the appropriatearyl halocarbonyl ketene (0.1 mole) in methylene chloride (sufficient toprovide a clear solution and generally from about 5 to 10 ml. per gramof ketene) there is added the proper alcohol R OH (0.1 mole). Thereaction mixture is maintained under an atmosphere of nitrogen andstirred for a period of from 20 minutes to 3 hours, care being taken toexclude moisture. The temperature may range from about C. to about 20 C.The infrared spectrum of the mixture is then taken to determine andconfirm the presence of the ketene ester. A solution of6-aminopenicillanic acid-triethylamine salt (0.1 mole) inmethylenechloride (50 ml.) is added and the mixture stirred at 70 to 20C. for ten minutes. The cooling bath is then removed and the reactionmixture stirred continuously and allowed to warm to room temperature.The product is isolated by one of the methods below.

Method A: The reaction mixture is evaporated to dryness under reducedpressure and the residue taken up in citrate bulTer (pH 5.5). Theproduct is extracted from the buffer solution with chloroform. Thechloroform extract is washed with citrate buffer (pH 5.5) then driedwith anhydrous sodium sulfate and evaporated to dryness to give thesodium salt.

Method B: The procedure of Method A is followed but using n-butanol asextracting solvent in place of chloroform. The product obtained afterevaporation of the n-butanol solvent is triturated with ether to give anamorphous solid.

Method C: This procedure, a variation of Method A, uses a saturatedaqueous solution of sodium (or potassium) bicarbonate in place ofcitrate buffer to produce the sodium (or potassium) salt of thepenicillin product. It is generally used for the recovery of thosepenicillin prod- Method EXAMPLE XIII The sodium and potassium salts ofExamples IX-XII are converted to the corresponding acids by carefulneutralization of aqueous solutions of their salts with aqueousphosphoric acid followed by extraction of the acid form intomethylisobutylketone. The methylisobutylketone solutions are washed withwater, dried with anhydrous sodium sulfate, filtered and evaporated togive the free acids.

EXAMPLE XIV The free acids of Examples IX-XIII are converted to theircalcium, magnesium, ammonium, procaine, N,N-dibenzylethylenediamine,N-ethylpiperidine, dibenzylamine, l-ephenamine, triethylamine,N-benzyl-fi-phenethylamine, N,N-bis(dehydroabietyl)ethylenediamine andbenzhydrylamine salts by reaction of aqueous solutions thereof with oneequivalent of the appropriate base. The salts are recovered by freezedrying.

EXAMPLE XV A solution of the sodium salt of OL-[C3l'bO(1-thOXy-2,2,2-trichloroethoxy)]benzyl penicillin (0.5 g.) in a small volume ofsaturated aqueous sodium bicarbonate (5 ml.) is stirred at roomtemperature. Samples are withdrawn at minutes, minutes and then athalf-hour intervals and examined by paper chromatography in the systemisoamyl acetate:citrate-phosphate buffer (pH 4.5) and by bioautographs(Bacillus subtilis). The samples are also extracted with chloroform (3X3ml.), the combined extracts concentrated and the concentrate and thespent aqueous sample examined by paper chromatography and bioautographs.

Hydrolysis of the ester is essentially complete within two hours asevidenced by the absence of the ester on the papergram and the presenceof a-carboxy benzyl penicillin along with a small amount of benzylpenicillin.

EXAMPLE XVI A solution of the sodium salt ofa-[carbo-(dicarbethoxyethoxymethoxyJbenzyl penicillin in water (0.5 g.in 10 ml.) is held at room temperature for 24 hours. The pH isautomatically regulated at 7.0-7.2 by the addition of sodiumbicarbonate. The solution is then freeze dried and the by-product phenolremoved by trituration of the residue with ethanol to give the disodiumsalt.

Repetition of this procedure but at C. for two hours also produces thedisodium salt.

EXAMPLE XVII A tablet base is prepared by blending the followingingredients in the proportion by weight indicated.

Sucrose, U.S.P. 80.3 Tapioca starch 13.2 Magnesium stearate 6.5

Suificient a [carbo(l ethoxy 2,2,2 trichloroethoxy)]benzyl penicillinsodium salt is blended into the base to provide tablets containing 25,and 250 mg. of active ingredient.

EXAMPLE XVIII Capsules containing 25, 100 and 250 mg. of activeingredient are prepared by blending sufficienta-[carbo(dicarbethoxyethoxymethoxy)]benzyl penicillin sodium salt in thefollowing mixture (proportions given in parts by weight).

Calcium carbonate, U.S.P. 17.6 Dicalcium phosphate 18.8 Magnesiumtrisilicate 5.2 Lactose, U.S.P. 5.2 Potato starch 5.2 Magnesium stearateA 0.8 Magnesium stearate B 0.35

EXAMPLE XIX A suspension of a-[carbo(l-ethoxy 2,2,2 trichloroethoxy)]benzyl penicillin sodium salt is prepared with the followingcomposition:

Penicillin compound g 31.42 70% aqueous sorbitol g 714.29 Glycerine,U.S.P. g 185.35 Gum acacia (10% solution) ml 100 Polyvinyl pyrrolidone g0.5 Butyl parahydroxybenzoate g 0.172 Propyl parahydroxybenzoate g 0.094

Distilled water to make one liter.

Various sweetening and flavoring agents may be added to this suspension,as well as acceptable colors. The suspension contains approximately 25mg. of penicillin compound per milliliter.

EXAMPLE XX The sodium salt of a [carbo (2,2,2 trifluoroethoxy)]benzylpenicillin (10 g.) is intimately mixed and ground with sodium citrate(4% by weight). The ground, dry mixture is filled into vials, sterilizedwith ethylene oxide and the vials sterilely stoppered. For parenteral administration, sufficient water is added to the vials to form solutionscontaining 25 mg. of active ingredient per ml.

Preparation A.Malonic acids The following aryl malonic acids notpreviously described in the literature are prepared by the method ofWallingford et al., J. Am. Chem. Soc. 63, 20562059 (1964) whichcomprises condensing an alkyl carbonate, usually diethyl carbonate, withan equimolar proportion of the desired ethyl aryl acetate in thepresence of an excess (4-8 times) of sodium ethylate with continuousremoval of by-product alcohol from the reaction mixture. The esters thusproduced are hydrolyzed to the acid by knOWn methods.

COOH

Ih-CH COOH 3-pyridyl 4-pyridyl a-butoxyphenyl r-dimethylarninophenylu-diethylaminophenyl m-dimethylaminophenyl p-dirnethylaminophenyla-dibutyl aminophenyl The appropriate (lower)alkylmercaptoalkanol ismixed with an equimolar proportion of m-chloroperbenzoic acid insufficient chloroform to permit easy stirring. The mixture is refluxedfor two hours, then cooled overnight and filtered to removem-chlorobenzoic acid. The filtrate is then concentrated to aboutone-third volume, allowed to stand overnight and again filtered toremove in-chlorobenzoic acid. The filtrate was added to water (3 to 4ml. per ml. of filtrate), stirred thoroughly and again filtered. Theproduct is recovered from the filtrate by removal of the solvent. Inthis manner the following compounds are prepared:

Other peracids such as acetic acid, performic acid and monoperphthalicacid, and hydrogen peroxide in glacial acetic acid can be used in placeof m-chloroperbenzoic acid. This latter peracid is, however, favoredsince the by product m-chlorbenzoic is easily removed and over-oxidationof the mercaptan to the dioxide avoided.

Preparation C.Preparation of (lower)alkylsulfonylalkanols (l) Thedesired (lower)alkylmercaptoalkanol is oxidized according to the methodof Preparation B but using two molar proportions of m-chlorobenzoic acidinstead of one as oxidizing agent.

(2) Alternatively, the (lower)alkylsulfinylalkanols of preparation B arefurther oxidized with an equimolar proportion of rn-chloroperbenzoicacid to the corresponding sulfonyl compounds. The former method ispreferred because of the greater availability of the initial mercaptansrelative to the sulfinyl compounds.

The following compounds are thus prepared:

and the pharmaceutically acceptable salts thereof wherein R is phenyl;and R is substituted (lower)alkyl wherein the substituent is selectedfrom the group consisting of at least one of: (lower)alkoxy, chloro,carbo(lower)alkoxy.

2. The compounds of claim 1 wherein R is (lower) alkyl substituted with(lower)alkoxy and chloro.

3. The compounds of claim 1 wherein R is (lower) alkyl substituted with(lower)alkoxy and carbo(lower) alkoxy.

4. The compounds of claim 2 wherein R is 1-butoxy- 2,2,2-trichloroethyl.

5. The compounds of claim 3 wherein R is dicarbethoxyethoxymethyl.

6. The compound of claim 2 wherein R is l-ethoxy- 2,2,2-trichloroethyl.

7. The compounds of claim 4 wherein R is carbethoxyethoxymethyl.

8. The compound of claim 2 wherein R isl-isopropoxy,2,2,2-trichloroethyl.

References (Cited UNITED STATES PATENTS 3,282,926 11/1966 Brain et al260-239.1 3,502,656 5/1970 Neal et al. 260239.1

OTHER REFERENCES 1,125,557 8/1968 Great Britain 260239.1 1,160,2118/1969 Great Britain 260239.1

NICHOLAS S. RIZZO, Primary Examiner US. Cl. X.R. 424-271 Dedication.Kenneth Butler, Waterford, Conn. SUBSTITUTED ALKYL ESTERS OF a-CARBOXYARYL PENIOILLINS. Patent dated J an. 19, 1971. Dedication filed Oct. 31,1971, by the assignee, Pfizer Inc. Hereby dedicates to the Public theentire remaining term of said patent [Ofiicial Gazette December 28,1971.]

